Automatic pitch change propeller



April 3, 1951 o. B. MORELOCK AUTOMATIC PITCH CHANGE PROPELLER 5 Sheets-Sheet 2 Filed Nov. 19, 1945 INVENTOR DEER E. MUHE'LUEK ATTORNEY April 3, 1951 o. B. MORELOCK AUTOMATIC PITCH CHANGE PROPELLER I s Sheets-Sheet 5 INVENTOR E15 ER 5. MUHELUEK ATTORNEY Filed NOV. 19, 1945 Patented Apr. 3, 1951 UNITED STATES PATENT OFFICE (Granted under the act of March 3, 1833, as amended April 30, 19218; 370 0. G. 757) 11 Claims.

This invention relates to automatic propellers and more particularly to operating mechanisms for varying and controlling the pitch of the same.

An object of the invention is to provide an improved propeller of simple, light-weight construction and adapted to be automatically controlled while in operation by the centrifugal force generated by its rotation.

Other objects of the invention are to provide an improved automatic propeller having means responsive to centrifugal action for controlling the pitch of the same together with co-operative means for moving the propeller into full feathered position whereby the pitch may be varied in accordance with the speed of rotation of said propeller; to provide an improved operating mechanism for automatically varying and controlling the pitch of a propeller during the operation of the same and being of such construction as to be housed primarily in the blades of the propeller and thereby be spaced a greater distance from the axis thereof, so as to be more sensitive to centrifugal action; to provide an improved opcrating mechanism having coacting weight and cam means in each propeller blade for varying and controlling the pitch of the blade together with resilient means for maintaining said blade in a fixed position whereby the pitch of the blade at constant speeds is automatically adjusted in accordance with such speeds; to provide an improved operating mechanism, of thecharacter described, having hydraulic means adapted to coact with the weight and cam means for increasing the pitch of the blade to permit full feathering of the same; to provide an improved operating mechanism, of the character described, having means for varying the tension of the resilient means so as to permit alteration of the constant speed pitch of the blade; and to provide improved elements and arrangements thereof in a propeller operating mechanism of the character described the line 3 3 of Fig. 1.-

Fig. 4' isan elevational view of a portion of the operating mechanism housing, showing the cam slots in overlying relation.

Fig. 5 is an end elevational view of the weight removed from the housing.

,Fig. 6 is a transverse, sectional view, taken on the line 6-6 of Fig. 1.

Fig. '7 is an enlarged, sectional view, showing the relation of the thrust collar and ring.

Fig. 8 is a transverse, sectional View, taken on the line 8--8 of Fig. 5.

Referring more in detail to the drawings:

In Fig. l, the numeral i designates the hollow crankshaft of an aircraft engine, the nose section of which is shown at 2 (Figs. 2 and 3). A propeller hub 3, having an axial bore t, is splined upon the crankshaft l and is maintained thereon by a centering cone 5 and a retaining nut 6 which is screw-threaded upon the outer end of said crankshaft (Fig. 2). The hub 3 has a plurality of cylindrical, radial arms or sockets l, which are preferably equally-spaced and which have been illustrated as being a trio, although such quantity is manifestly subject to variation. A circular boss or stub spider 8 is formed axially within each socket l at its base and is preferably externally,

screw-threaded for receiving and supporting an operating mechanism 9, as will be described hereinafter.

A hollow blade Hi, having a cylindrical shank or root 1 l, is rotatably mounted in each socket l with its root concentrically surrounding the stub spider 8. The inner end of the blade root It is provided with a radial, bevelled shoulder l2 which has a snug fit within the socket. A plurality of annular spacers or rings 13 and one or more thrust bearing assemblies l4 encircle the blade root andare confined within the socket by a retaining nut l5 screw-threaded in the outer end of said socket.

The pitch or angular position of the blades lil is synchronized by a bevelled idling gear It (Fig.

portion of each blade root shoulder l2.

2) having its teeth in constant mesh with complementary gear teeth I! formed on an arcuate A chamber or recess i8 is formed in the forward portion of the hub 3 for receiving the gear I5 and is closed.

by an overlying, circular cover plate 19 which is fastened to said hub by suitable screws 20. The

4 plane perpendicular to the longitudinal axis of the crankshaft I; whereas, when installed, the

3 blade is rotated approximately 26 in a clockwise direction, as viewed from the bottom of Fig. 1, whereby said blade has a normal pitch of substantially 20 with the leading edge 22 being disposed forwardly to the right and the trailing edge 23 rearwardly to the left. As a result, the various elements of the operating mechanism 9 occupy complementary positions.

Each blade it has a longitudinal bore 24 extending throughout its root ii and into at least its intermediate portion. Each operating mechanism 9 includes an elongated, cylindrical shell or housing '25 axially disposed within the blade bore 24 and having its inner end screw-threaded upon the stub spider 8. A fiat cap or circular plate 25 is fastened to and closes the outer end of the housing 25. Slidably mounted within the outer portion of the housing is a circular disc or weight El which is responsive to the centritrifugal force generated by rotation of the hub 3.

For rotating the weight upon sliding movement of the same, a pair of diametrically-opposed lugs or arms 28 project radially from the peripheral surface of said weight (Fig. and engage within angular, helix or cam slots 29 formed in the outer end portion of the housing (Fig. 4). The cam slots 29 are diametrically-opposed and extend at acute angles, approximately 38?, to the longitudinal axis of the housing in a clockwise direction as viewed from the bottom of Fig. 4. Each slot has an outer portion or leg 3% of increased anguiarity, which leg extends at an acute angle to the slot and the longitudinal axis of the housing and has its outer end closed by the cap 26.

As shown in Fig. 5, a ball bearing assembly 3! is mounted transversely upon'the outer end of each weight arm 28 externally of the housing and the bearings engage within longitudinal guide members or channel bars 32 secured within the blade bore Z l in diametrically-opposed relation,

whereby the blade is rotated upon its longitudinal axis by sliding movement of the weight. It is preferable for the channel bars 32 to be aligned with the leading and trailing edges of the blade Since the cam slots 29 i as shown in Fig. i. extend in a clockwise direction, the leading edge of the blade moves forwardly to the right and the trailing edge moves rearwardly to the left upon outward sliding of the weight under the innuence of centrifugal action.

For resisting outward movement of the weight, a coiled or helical, tension spring 33 has one of its ends fastened to the fiat inner surface of said weight by a suitable annular clip 3 The inner or opposite end of the tension spring 33 is secured by a similar clip 35 to an anchor member or disc 35 which is preferably circular and is mounted transversely in the housing 25 inwardly of the weight. As will be hereinafter more fully explained, the tension spring coacts with the cam slots to maintain the blade in predetermined positions at constant speed of rotation. Diametrisally-opposed lugs or arms 3? project radially from the peripheral surface of the disc 36 through longitudinal openings or slots 33 formed in the housing (Fig. 6), whereby rotation of said disc relative to said housing is prevented. The outer end surfaces of the arms 31 are bevelled or arced and have helical teeth or threads 39 formed thereon.

For adjusting the position of the anchor disc longitudinally of the housing and relative to the weight so as tovary the tension of the spring 33, a cylindrical sleeve 49 is rotatably. confined upon the inner portion of said housing by an external.

i radial shoulder 4H which is formed on the housing outwardly of its longitudinal slots 38. The outer portion of the sleeve ii) overlies the longitudinal slots and is provided with internal screw-threads 32 for meshing with the threads 39 of the disc arms. Due to this arrangement, rotation of the sleeve moves the disc longitudinally of the housing and relative to the weight so as to vary the spring tension. I

The sleeve is adapted to be rotated by a gear rack or bar 43 which has its teeth in constant mesh with the teeth of an arc-uate gear segment or section #34 formed on the peripheral inner end portion of said sleeve. As is clearly shown in Figs. 2 and 3, the gear rack 43 is slidably mounted in the hub 3 transversely of the sockets l by means of suitable bearing collars or bushings 45 and projects rearwardly toward the engine nose section 2.

An annular thrust collar 45 concentrically surrounds the crankshaft 'l rearwardly of thehub and ha connection with the gear rack of each blade operating mechanism 9 for simultaneously imparting sliding movement to the gear racks. The collar 48 is moved longitudinally of its axis by means of a forked or yoke-shaped, operating lever 31 which is pivotally connected to said collar as at $8 and to the engine nose section 2 as shown by the numeral is. Any suitable means (not shown) may be connected to the lever 49 for permitting actuation of the same by the pilot.

An annular member or ring 59, which is channel-shaped in cross-section, is secured to the inner end of each gear rack and concentrically surrounds the thrust collar as shown in' Fig. 7. For rotatably supporting the ring 50', a ball bearing assembly 5! is confined withinsaid ring and includes an inner race 52 pressed upon the external periphery of the thrust collar so as to be non-rotatable. 'An outer, rotatable race 53 is supported by a plurality of balls 54 in the usual manner so as to be rotatable with the ring and gear racks. In order to transmit longitudinal movement from the thrust collar to the ring without binding of the bearing assembly 5!, the inner portion of the channel of said ring'is of decreased width as shown by the numeral 55' so-as to "be readily engaged by the outer race 53 upon such longitudinal movement.

As shown in Fig. i, an actuating element or rod 56 is disposed axially within the housing 25 and extends from the inner end thereof to a point adjacent the weight 2?. The intermediate portion of the rod 56 is squared or angular in crosssection as shown by the numeral 5'5 and engages within a complementary opening :58 formed axially in the anchor disc 3%, whereby rotation of said rod is prevented. A circular recess 59 (Figs. 5 and 8) is formed axially in the inner surface of the weight 2'? for receiving the outer end of the rod which is of reduced diameter and has a diametric or transverse foot or lug 60 secured thereto (Fig. 1). The annular clip 34, which fastens the outer end of-the tension-spring 33 to the weight, externally surrounds therecess 59 and permits passage of the lug 69 into and out of said recess, as will be hereinafter explained. In order to lock the rod to the weight, a pair of lips or flanges El overlie the recess and provide an opening or slot l'l for accommodating the lug.

A circular plate or pistonifiz is screw-threaded upon or otherwise secured to the inner end of the rod and has a snug sliding fit within the inner portion of the housing 25. Thisportion-of the housing functions as a hydrauliccylinder B3 and is in communication with an axial port 64 formed in the stub spider 8. A coiled or helical compression spring to is confined upon the rod between the anchor disc 35 and the piston 62 for urging and maintaining said piston inwardly of the cylinder $33.

As is most clearly shown in Fig. 2, a transverse port 66 establishes communication between the axial port d and the hub recess 18 and the latter communicates with the bore of the crankshaft i. Oil or other fluid is forced under pressure by a suitable pump 8! from a reservoir 63 through a tube or conduit 69 to a stationary oil transfer ring 'Hl which snugly encircles the crankshaft internally of the engine nose section 2. The oil ring 70 has a radial port or opening H for receiving the free end of the conduit 69 and is disposed in the same vertical plane as a plurality of complementary ports l2 formed in the crankshaft, whereby the ports register with the opening upon rotation of said crankshaft so as to admit oil to the bore thereof.

Since the lug 68 of the rod lib is disconnected from the recess 59 of the weight 2i, said rod and its piston 62 remain stationary upon outward movement of said weight. the piston and rod by the pressure of the oil forced into the cylinder 53 by the pump 6? causes the lug of said rod to pass through the slot ltd into the recess of the weight so as to move the arms 28 of said weight into the slot legs 3!], thereby rotating the weight an additional 40 and increasing the pitch or the blade it to approximately 90 or its full-feathered position. The compression spring 85 is compressed by this outward movement and the rotation of the weight engages the lug beneath the flanges ti so as to lock the rod to said weight. Upon release of the oil pressure, the compression of the spring forces the piston and rod inwardly so as to retrieve the weight arms from the slot legs, rotate the weight in a reverse direction and thereby decrease the pitch of the blade.

Operation The operation of a propeller constructed as described is as follows:

The blades it normally have a pitch of approximately 20 with each blade having its leading edge 22 disposed forwardly to the right and its trailing edge 23 rearwardly to the left, relative to its respective socket 1 (Fig. 1). Upon rotation of the crankshaft i and hub 3, centrifugal action forces each weight 27 longitudinally outwardly of its housing and the engagement of the weight arms 28 within the cam slots 29 causes an approximate 30 clockwise rotation of the weight. Due to the engagement of the bearing assemblies 3i within the channel bars 32, each blade rotates with its weight so as to have its pitch increased to approximately 50.

Each tension spring 33 is constantly resisting outward movement of each weight due to its connection to the weight and its anchor disc 36' by the clips 34 and 35. When the pitch of the blades is sufiicient to reduce the speed of rotation of the propeller, the tension of the springs overcomes the centrifugal force of the weights so as to move the same inwardly and thereby decrease the pitch of said blades. Thus, the pitch of the blades is automatically adjusted at constant speeds of rotation. Due to the provision of the idling gear l5 and the gear teeth ll on each blade root shoulder I 2, the pitch of the blades is in constant synchronization.

Outward movement of The tension of each spring 33 is varied by longitudinal adjustment of its anchor disc 36 so as to alter the constant speed pitch of each blade. Since the anchor disc is held stationary by the engagement of its arms 3! in the longitudinal slots 3% of the housing (Fig. 6), rotation of the sleeve ii! results in longitudinal adjustment of said anchor disc. Pivoting of the lever d? moves the thrust collar d6 axially so as to engage the outer bearing race 53 with the ring 59 and there by impart longitudinal reciprocation to the gear racks as (Figs. 1, 2, 3 and 7). The gear sector 4-4 of each sleeve, which meshes with one of the gear racks, converts the motion of the latter into rotation of the sleeve and the anchor disc is moved longitudinally by the engagement of the threads 39 of its arms with the internal screwthreads 42 of said sleeve.

Since the lug Gil is detached from the weight recess 59, the rod 56 and its piston 82 remain stationary upon this movement of the weight relative to the housing and anchor disc. When it is desired to increase the pitch of the blades to their full-feathered positions, the pump 61 is operated to force oil or other fluid under pressure from the reservoir 6% through the conduit 69, oil ring ill, opening H and ports 12 into the bore of theerankshaft i (Fig. 2). The hub recess ill and ports 86 and 64 conduct the oil to the cylinder 63 of each operating mechanism 9, whereby the piston and rod are forced outwardly to engage the rod lu within the weight recess and move the weight outwardly.

Due to this latter movement, the weight arms travel outwardly of the cam slots and into. the outer legs 3!! thereof (Figs. 1 and 6), thereby increasing the pitch of each blade an additional 40 to approximately or its full-feathered position. The blades are returned to their constant speed pitch by releasing the oil pressure so that the compression of each spring 65 exerted against its respective piston moves said piston, the rod and weight inwardly. The angular portion 51 of therod and the complementary opening 58 of the anchor disc prevent rotation of said rod and relative rotation of the weight is permitted by the circular shape of the weight recess. i

While I have shown but one embodiment of my invention, it is susceptible to modification without departing from the spirit of the invention. I do not wish, therefore, to be limited by the disclosures set forth, but only by the scope of the appended claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor. l

I claim.

1. An automatic propeller including, a hub having an axial bore and a'plurality of radial equally-spaced sockets, a stub spider formed in each socket, a blade having its root rotatably mounted in each socket in concentric relation to the stub spider, gear teeth formed on the root of each blade, an idling gear axially aligned with the hub bore and rotatably supported in meshing engagement with the gear teeth of the blade roots for synchronizing the pitch of said blades, each blade having a longitudinal bore, an operating mechanism including, a cylindrical housing connected to each stub spider and axially disposed "in the blade bore, the housing having 7 thereof, the outer portions of the slots being of greater angularity than the inner portions thereof, a weight slidably disposed within said housing and having radial portions extending through said slots, a pair of diametrically-opposed channels secured within said blade bore for receiving and coacting with the radial portions of the weight, whereby the centrifugal action generated by rotation of the propeller causes outward movement of said weight and the engagement of its radial portions within the slots and channels causes rotation of the blade upon its longitudinal axis so as to vary its pitch, an anchor disc disposed within the housing, a helical tension spring fastening the weight to the disc for resisting outward movement of said weight and maintaining said blade in predetermined position at constant speeds of rotation, said housing having longitudinal slots formed therein adjacent said disc, radial lugs formed on the disc and rojecting through the slots, a sleeve rotatably surrounding the housing and having an internally screw-threaded portion overlying said longitudinal slots, the lugs having complementary threads on their outer extremities engaging the screw-threaded portion of the sleeve, whereby rotation of said sleeve causes longitudinal movement of said disc relative tothe weight for varying the tension of the spring, an axial rod having an angular portion slidable through the disc for preventing rotation of the rod, gear teeth formed on the inner end of the sleeve, a transverse gear rack slidably mounted in the hub and having its teeth meshing with the gear teeth of said sleeve, a thrust collar mounted rearwardly of said hub and adapted to undergo axial reciprocation, a manually-operated lever for reciprocating the collar, said collar having connection with the gear rack whereby the latter may be slid longitudinally to rotate the sleeve for moving the disc longitudinally and varying said spring tension, a piston secured to the inner end of the rod and slidably mounted in said sleeve, a helical compression spring confined upon said rod between the piston and said disc for urgin said piston inwardly of the hub, the stub spider having an axial port communicating with the interior of the sleeve inwardly of the piston, a transverse port formed in said. hub for establishing communication between its bore and the axial port, a pump for forcing fluid under pressure through the hub bore and the ports into said sleeve for sliding said piston outwardly of the sleeve and the outer end of the axial rod into engagement with the weight, whereby outward sliding of the piston causes outward movement of said weight'beyond the inner portions of the helix slots and the engagement of its radial portions in the outer portions of said helix slots and in the channels of the blade causes further rotation of said blade upon its longitudinal axis so as to increase its pitch, a diametric lug formed on said rod outer end, the weight having an axial circular recess in its inner surface for receiving the lug, and means overlying the recess for accommodating the lug and locking the same in said recess upon outward movement of said weight by said piston, whereby the compression spring returns the weight inwardly of the helix slots to the inner portions thereof so as to rotate the blade in a reverse direction and decrease the pitch thereof.

2. In a propeller having a hub with an axial bore and a plurality of radial sockets, a stub spider formed concentrically in each socket, each spider having an angular port communicating with the hub bore, a punip for forcing fluid under pressure into said hub bore, a blade rotatably mounted in each bore and having a longitudinal bore, gear teeth formed on the inner end of the blade, a synchronizing gear rotatably mounted in axial alignment with the hub bore and in meshing engagement with the blade teeth, the combination of an operating mechanism including a cylindrical housing screw-threaded upon each stub spider so as to extend axially of the blade bore, the housing having cam slots formed therein extending at acute angles to the 1ongitudinal axis thereof, the outer portions of the slots being of greater angularity than the inner portions thereof, a weight slidable longitudinally of said housing, lugs projecting radially from the Weight through the inner portions of the slots, channel members mounted in the blade bore for receiving and coacting with the weight lugs, whereby said weight moves outwardlyof the housing and blade due to centrifugal force created by rotation of the propeller and rotates said blade upon its longitudinal axis to increase its pitch due to the coaction of said lugs with said slots and channel members, an anchor member disposed within the housing, a tension spring fastening the weight to the anchor member for resisting outward movement of said weight and maintaining said blade in predetermined positions at constant speeds of rotation, said housing having openings therein adjacent said anchor member, lugs projectin radially from the anchor member through the housing openings and having screw threads on their outer ends, a sleeve rotatably surrounding the housing and having internal screw-threads overlying said openings so as to engage the screw-threaded end of the lugs whereby rotation of the sleeve causes longitudinal movement of said anchor member relative to the weight for varying the tension of the spring, a rod having an angular portion slidable through the anchor member for preventing rotation of the rod, gear means associated with the inner end of said sleeve for rotating the same, a piston mounted on the inner end of the rod and reciprocable within said housing so as to be exposed to the fluid forced through the angular port of the stub spider, whereby the piston and rod may be moved outwardly of the housing by said pressure fluid to engage the outer end of said rod with said weight so as to move the same beyond the inner portions of the cam slots whereby the lugs of the weight engage the outer portions of said slots to rotate the blade and increase the pitch thereof, 00- acting means carried by said rod outer end and said weight for locking the same together, and a compression spring confined upon the rod between the piston and anchor means for urging said piston and rod inwardly to retract the weight and rotate the same with the blade in a reverse direction so as to decrease the pitch of said blade.

3. In a propeller having a hub with an axial bore and a plurality of radial sockets, a stub spider formed concentrically in each socket, each spider having an angular port communicating with the hub bore, a pump for forcing fluid under pressure into said hub bore, a blade rotatably mounted in each bore and having a longitudinal bore, gear teeth formed on the inner end of the blade, a synchronizing gear rotatably mounted in axial alignment with the hub bore and in meshing engagement with the blade teeth, the combination of an operating mechanism ineluding a weight slidably mounted in the outer portion of the blade bore so as to be responsive to centrifugal action and having weight for rotating the blade and varying the pitch thereof upon sliding movement of said weight, anchor means disposed in said blade bore, resilient means fastening the weight to the anchor means for resisting outward movement of said weight and coacting with the cam means to maintain the weight and blade in predetermined positions at constant speeds of rotation, means having connection with the anchor means for maintaining the samein a fixed position and bein adjustable so as to move said anchor means relative to said weight for varying the tension of the resilient -means, I piston means reciprocably mounted in the blade bore and exposed to the pressure fluid forced through the angular port of the stub spider so as to be moved outwardly of said blade by said pressure fluid, resilient means interposed between the piston means and the anchor means for resisting outward movementoi said piston m eansand urging the same inwardly upon exhaust of the pressure fluid, and means detachably connecting the piston means to-the weight whereby-outward movement of said, piston means slides said weight outwardly to -further vary the pitch of the blade.

he, in a propeller having a hub with an axial bore and aplurality of radial sockets, a stub spider formed concentrically in each socket, each spider having an angular port communicating with the hub bore, a pump for forcing fluid under pressure into said hub bore, a blade rotatably mounted in each bore and having a longitudinal bore, gear teeth formed on the inner end of the blade, 9, synchronizing gear rotatably mounted in axial-alignment with the hub bore and in meshing engagement with the blade teeth, the combination of, a noperating mechanism including, a weight slidably mounted in the outer portion of the blade bore so as to be responsive to centrifugal action, the weight-having connection with said bl'adanieans engaged by said weight for rotati'ng the blade and varying the pitch thereof fupon. sliding movementof the weight, resilient means engaging said weight to resist outward movement thereof, pressure responsive means 'slidably mounted in the blade bore and exposed to the pressure fluid forced through the angular port of the stub spider so as to be slid outwardly or" the blade by said pressure fluid, resilient means engaging said pressure-responsive means to resist outward movement thereof and to urge the same inwardly upon release of the pressure fluid, and means detachably connecting said pressure responsive means to said weight, whereby outward monument of the pressure responsive means slides the weight outwardly to further vary the pitch of said blade.

5. In a propeller having a hub with an axial bore and a plurality of radial sockets, a stub spider formed concentrically in each socket, each spider having an angular port communicating with th hub bore, a pump for forcing fluid under pressure into said hub bore, a blade rotatably mounted in each bore and having a longitudinal bore, gear teeth formed on the inner end of the blade, a synchronizing gear otatably mounted in alignment with the hub bore and in meshing engagement with the blade teeth, the combination of an operating mechanism including, a weight slidably mounted in the outer portion of the blade bore so as to be responsive to centrifugal action, means connecting the Weight to said blade, cam

means coacting with said weight for rotating the weight and blade so as to vary the pitch of said blade upon sliding movement of said weight, an anchor disc disposed in said blade bore, a tension spring fastening the weight to the anchor disc for resisting outward movement of said weight and coasting with the cam means to maintain the weight and blad in predetermined positions at constant speeds of rotation, means having screw-threaded connection with said disc for maintaining the same in a fixed position and being adjustable for moving the disc relative to said weight for varying the tension of the spring, a cylinder within the blade bore and co-mmuni cating with the angular port of the stub spider, a piston slidab-ly mounted in the cylinder and exposed to the pressure fluid forced through said port into said cylinder and adapted to be slid outwardly by saidfluid, a rod connected to the piston and sildable through said disc, the outer end of said rod being adapted to engage the weight whereby outward sliding of said piston and rod moves said weight outwardly tofurther vary the pitch of the blade, means detachably connecting the rod to the weight, and a compression spring confined upon the rod between the piston and disc for resisting outward movement of said piston and urging the same inwardly upon release of the pressure fluid.

6. An operating mechanism for varying the pitch of a propeller having a hub with hollow blades rotatably mounted in the radial sockets of the hub, including: a weight slidably mounted in each blade so as to be responsive to centrifugal action, cam means coacting with the weight for rotating the same upon sliding movement thereof, the cam means extending at an acute angle to the'longitudinal axis of the blade the angularity of the outer portion of said cam means being greater than that of the inner portion, guide means connecting said weight to said blade whereby the blade rotateswith the weight and the pitch of said blade is varied, a tension spring engaging said weight to resist outward movement thereof, means for varying the tension of the spring, a hydraulic cylinder within the blade, a piston slidably mounted in the cylinder, means for forcing fluid under pressure into said cylinder so as to urge the piston outwardly of said blade, means detachably connecting said piston to said weight whereby the latter is moved outwardly by the piston and rotated by the outer portion of the cam means to increase the pitch of the blade, and a compression spring engaging said piston to resist outward sliding thereof and to urge the same inwardly upon release of the pressure fluid.

7. An operating mechanism for varying the pitch of a propeller having a hub with hollow blades rotatably mounted in the radial sockets of the hub including, a weight slidably mounted in each blade so as to be responsive to centrifugal action, the weight having connection with the blade, camineans coacting with said weight for rotating said blade and varying the pitch thereof upon sliding movement of the weight, tension means engaged with said weight to resist outward movement of said weight, pressure responsive means mounted in said blade, means for exposing the pressure responsive means to fluid under pressure so as to urge the same outwardly of the blade, compression means engaged with said pressure responsive means to esist outward move-- ment thereof and to urge the same inwardly upon release of the pressure fluid, and means connecting the pressure responsive means to the weight 11 whereby the same is slid by movement of said pressure responsive means and the pitch of said blade varied.

8. An operating mechanism for varying the pitch of a propeller having a hub with hollow blades rotatably mounted in the radial sockets of the hub including, a weight slidably mounted in each blade so as to be responsive to centrifugal action, the weight having connection with the blade, cam means coacting with said weight for rotating said blade and varying the pitch thereof upon sliding movement of the weight, tension means engaged with said weight to resist outward movement of said weight and coacting with the cam means to maintain the blade in predetermined positions at constant speeds of rotation a rod. longitudinally reciprocable in each blade, and having a portion which may be abutted against said weight to move the same outward against said tension means, and control means extending externally of the propeller for controlling movement of each said rod.

9. An operating mechanism for varying the pitch of a propeller having a hub with hollow blades rotatably mounted in the radial sockets of the hub including, a weight slidably mounted in each blade so as to be responsive to centrifugal action, the weight having connection with the blade, cam means coacting with said weight for rotataing said blade and varying the pitch thereof upon sliding movement of the weight, resilient means engaged with said weight to resist outward movement of said weight and coacting with the cam means to maintain the blade in predeerrnined positions at constant speeds of rotation, hydraulic means for urging the weight outwardly to further vary the pitch of said blade, and second resilient means resisting such outward movement.

10. An operating mechanism for varying the pitch of a propeller having a hub with hollow blades rotatably mounted in the radial sockets of the hub including, a weight freely slidable in each blade so as to be responsive to centrifugal action, cam means coacting with the weight for rotating the same upon sliding movement thereof, the cam means extending at an acute angle to the longitudinal axis of the blade, the outer portion of said cam means being of greater angularity than the inner portion, guide means for connecting said weight to said blade whereby the blade rotates with the weight and the pitch of said blade is varied, resilient means engaging said weight to bias the same toward the hub and co acting with the cam means to maintain the weight and blade in predetermined positions at constant speeds of rotation, and selectively operable hydraulic means engageable with the weight to move the same outwardly whereby said weight is rotated by the outer portion of the cam means to increase the pitch of said blade, said weight being under the control solely of centrifugal force and said resilient means, except when said hydraulic means is selectively operated.

11. An operating mechanism for varying the pitch of a propeller having a hub with hollow blades rotatably mounted in the radial sockets of the hub including, a weight slidably mounted in each blade so as to be responsive to centrifugal action, cam means coacting with the weight for rotating the same upon sliding movement thereof, the cam means extending at an acute angle to the longitudinal axis of the blade, the outer portion of said cam means having a greater angularity than the inner portion, guide means for connecting said weight to said blade whereby the blade rotates with the weight and the pitch of said blade is varied, and resilient means engaged with said weight to resist outward movement thereof and coacting with the cam means to maintain the weight and blade in predetermined positions at constant speeds of rotation, means independent of said weight for rotating said blade, and means mounted externally of said propeller for controlling said independent blade rotating means. 1

OBER. B. MORELOCK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,723,617 Hele-Shaw et a1. Aug. 6, 1929 2,139,982 Smith Dec. 13, 1938 2,174,717 Caldwell et al, Oct. 3, 1939 2,294,867 Bottrill Sept. 1, 1942 2,306,096 Vose Dec. 22, 1942 2,307,101 Blanchard et al. Jan. 5, 1943 2,416,541 Olman Feb. 25, 1947 FOREIGN PATENTS Number Country Date 279,664 Great Britain Nov. 3, 1927 

